The present invention relates to a model generation method and a model generation apparatus of a semiconductor device, and in particular, relates to a model generation method and a model generation apparatus for generating a semiconductor device model used for power supply noise analysis.
When a current flows through a power supply wiring network in a semiconductor device and power is consumed by transistor elements in the device, the power supplied to each transistor element and a ground is subject to a voltage fluctuation. The voltage fluctuation affects characteristics of elements as a voltage noise and also affects yields of semiconductor devices. Particularly with a falling rated supply voltage in recent years, it is becoming more difficult to ignore the voltage fluctuation. Therefore, desired performance cannot always be achieved if the influence by power supply noise is not analyzed with enough precision in the design process. In addition, a problem of reworking and the like due to a redesign may arise. Thus, power supply noise analysis using a high-precision model in the design stage is important.
To perform a high-precision power supply noise analysis, power supply noise analysis simulations of a large-scaled LSI (Large-Scale Integration) using a transistor model such as an SPICE (Simulation Program with Integrated Circuit Emphasis) model can be considered. However, such a large-scale analysis using such a transistor model (without modification) causes a problem of time and resources needed for the analysis and thus, its implementation is not easy.
Thus, a circuit is divided into parts, and then a power supply noise analysis is performed for each part based on the transistor model. A a method of performing a power supply noise analysis by dividing a semiconductor device intended for the power supply noise analysis into a power supply line, an internal capacity, an internal consumption current, and an input/output cell, generating an analysis model for each as a sub-model, and creating a model for power supply noise analysis by combining the generated sub-models is also known.
Moreover, a noise analysis performed by modeling signal waveforms in a semiconductor device is known. For example, a method of generating noise waveforms by adding a generation timing window of each type of noise has been proposed to properly calculate noise caused by mutual interference waveforms (crosstalk) regarding crosstalk of signal voltages propagated by signal lines arranged nearby in a semiconductor device.